The transfer of the cargo to or from one moving platform or craft such as a large ship or the like has always been difficult especially under adverse water conditions where there may be large waves. The transfer of cargo and the like is made even more difficult when such transfer is made from one watercraft to another watercraft. Although such transfers are inherently difficult they are of necessity carried out, even under severely adverse weather and water conditions when it is necessary.
Such transfers are commonly carried out through the use of cranes that have a boom with a line or lines extending from the end of the boom. Although cranes and in particular their booms appear to be structures that possess inherent strength, the booms are not designed to withstand undue side loadings or forces since they are primarily designed to lift certain loads in substantially a vertical plane. Consequently, excessive side loading caused by pendulation can result in structural failure of the boom with obvious serious effects.
Even if the boom of the crane should be capable of being subjected to the loads resulting from pendulation, the cargo can be easily damaged by impact and in addition such pendulation can cause damage to the transfer or transferring unit and/or the personnel or cargo located on the same. In addition, cargo pendulation problems can result in serious cargo transfer delays which can result in serious detrimental results particularly where the rapid transfer of cargo is essential such as would be the case in certain military or naval operations. Indeed, certain weather or sea conditions could absolutely prevent or seriously curtail certain cargo transfer operations to such an extent that the military or naval operation would fail or be seriously hampered as a result of these adverse conditions.
It is also desirable under certain conditions where pendulation is or is not a dominant factor not to have to raise or lower the boom during the operation of the cranes as is the case in connection with the current cranes.
The crane apparatus of this invention overcomes the previously noted deficiencies and provides apparatus that essentially permit the transfer of cargo without regard to the sea or weather conditions insofar as transfer of cargo between water vessels is concerned. Of course, the same is true with respect to any water to land or land to water transfer. In addition, the apparatus of the invention provide additional advantages in other related conventional operations.